Medical electrodes have wide clinical application in conjunction with a variety of electronic implantable medical devices such as pacemakers, cardiovertor defibrillators, neurostimulators, and ECG monitors. Medical leads may carry one or more electrodes used for sensing electrical signals in the body, such as intracardiac electrogram (EGM) signals, electrocardiogram (ECG) signals, and electromyogram (EGM) signals. Electrodes are also used for delivering therapeutic electrical stimulation pulses or for delivering electrical pulses used in electrophysiological mapping or for other diagnostic purposes.
The typical materials used in the manufacture of medical leads, such as, for example, metals such as platinum, titanium, tantalum, stainless steel, iridium, and alloys thereof, are not inherently biocompatible. The response of the body to such a foreign material can be aggressive, resulting in surface-induced thrombus formation. Thrombus formation on the lead can occur within days. Such thrombi can threaten patient health, particularly when they dislodge and travel via the circulatory system.
The left side of the heart pumps blood rich in oxygen to supply all parts of the body, while the right side of the heart pumps blood back to the lungs to pick up more oxygen. Clot formation on a lead placed in the systemic circulation of the left side of the heart can be clinically catastrophic, serving as a source of stroke in patients. While there are clinical applications in which lead placement in the systemic circulation would be advantageous, such left side placement is currently avoided, because of the substantial and potentially devastating risk presented by surface-induced thrombus formation. Thus, there is a clinical need for improved medical leads that are not prone to surface-induced thrombus formation and are suitable for left side placement.